WO2006103914A1

WO2006103914A1 - Exhaust gas purifier

Info

Publication number: WO2006103914A1
Application number: PCT/JP2006/304996
Authority: WO
Inventors: Toshihisa Kanda; Shogo Matsubayashi
Original assignee: Yanmar Co., Ltd.
Priority date: 2005-03-29
Filing date: 2006-03-14
Publication date: 2006-10-05
Also published as: US20090081087A1; CN102107113A; EP1867381A4; KR20070108269A; US20110138788A1; EP1867381A1; EP2279785A2; KR20090016737A; EP2279785A3

Abstract

It is intended to provide at low cost an exhaust gas purifier capable of in an internal combustion engine or other combustion equipment mainly driven under excess air conditions, efficiently removing nitrogen oxides from exhaust gas. Nitrogen oxide adsorbent (4) is disposed in an exhaust passage, which nitrogen oxide adsorbent (4) is composed of a lithium composite oxide of the general formula LiAxOy or LiAxPO4 containing as constituent elements lithium (Li) and at least one element (A) selected from the group consisting of manganese (Mn), nickel (Ni), cobalt (Co), vanadium (V), chromium (Cr), iron (Fe), titanium (Ti), scandium (Sc) and yttrium (Y). For example, the nitrogen oxide adsorbent is composed of a lithium composite oxide, such as lithium manganate (LiMn2O4), lithium titanate (Li2TiO3) or lithium manganese phosphate (LiMnPO4).

Description

Specification

Exhaust gas purification device

Technical field

The present invention relates to an apparatus for purifying exhaust gas from an internal combustion engine such as a diesel engine, a gas engine, a gasoline engine or a gas turbine engine, or a combustion device such as an incinerator or boiler, and in particular, performs normal operation in an excess air state. The present invention relates to an exhaust gas purification device that is installed in an exhaust passage of an internal combustion engine or the like and is suitable for removing nitrogen oxides.

Background art

[0002] Substances that are subject to exhaust gas purification are particulate substances such as nitrogen oxides, carbon monoxide, unburned hydrocarbons, and soot. Various devices for purifying these substances have been developed in the past. ing.

[0003] As a device for reducing nitrogen oxides (NOx), a reduction catalyst using ammonia or urea as a reducing agent is installed in the exhaust passage, and a denitration device that selectively reduces nitrogen oxides, etc. Has been put to practical use. In addition, relatively small gas engines and automobile gasoline engines have developed three-way catalysts that can simultaneously decompose nitrogen oxides, carbon monoxide (CO), and unburned hydrocarbons (HC). Contributes to effective purification of exhaust gas.

[0004] However, the three-way catalyst exhibits a purifying action effectively when operated within the stoichiometric air-fuel ratio or a range close thereto, but under other conditions, in particular, excessive exhaust of air (oxygen) It has been found that it does not work effectively in gas.

[0005] In order to cope with this, in a gas or gasoline engine operated in an excess air state, nitrogen oxide is temporarily stored in the storage material during operation in an excess air (oxygen) condition. A nitrogen oxide storage catalyst system that releases and reduces the stored nitrogen oxides by operating under excessive fuel conditions has been put into practical use.

[0006] As the catalyst of the above-described nitrogen oxide storage catalyst system, various combinations of noble metals and alkali metal oxides or alkaline earth metal oxides have been developed (see Patent Document 1 etc.). . These catalysts oxidize NO in the exhaust gas on the noble metal catalyst during the excessive air combustion (lean combustion) in normal operation, and the NO is alkali metal or It reacts with alkaline earth metal basic oxides and stores NOx as nitrates. In addition, NO desorbed from oxides during regeneration operation under rich fuel conditions (during rich operation) is reduced to N on noble metal catalysts by reducing substances such as hydrocarbons or CO, and released in a detoxified state. ing.

[0007] FIG. 15 shows a case where a nitrogen oxide storage catalyst in which a noble metal is combined with an alkali metal oxide or an alkaline earth metal oxide is used, and the nitrogen oxide storage catalyst is recovered from the regeneration operation. It is a graph showing the component ratio of released substances. About 75% is released as N, and the remaining 25% is released as N0x such as N0, N0 and N0.

Patent Document 1: JP 2001-000863 A

Disclosure of the invention

Problems to be solved by the invention

[0008] A denitration device that selectively reduces nitrogen oxides using ammonia, urea, or the like is applied to relatively large industrial internal combustion engines and combustion equipment. It is very expensive, and the maintenance cost of the reducing agents ammonia and urea is high. In addition, unconsumed ammonia is likely to be released into the atmosphere.

[0009] As described above, the three-way catalyst does not exert its catalytic function in an internal combustion engine or combustion equipment that is operated under an excess air condition.

[0010] In the nitrogen oxide storage catalyst system that is put into practical use in the small gas engine and the gasoline engine for automobiles, since the precious metal is always included as a component of the catalyst, the purification device becomes expensive and has a strong force. In addition, the operating range (temperature, SV value, etc.) that can be completely reduced is limited to a narrow range, and complicated lean-rich control (control of the supply amount of air and fuel) is required on the engine side.

[0011] (Object of invention)

It is an object of the present invention to provide an exhaust gas purification device that can efficiently remove nitrogen oxides in exhaust gas and render it harmless and discharged at low cost, mainly in an internal combustion engine or combustion equipment that operates under excessive air conditions. Is to do so. In addition, it is important to reduce the deterioration of the nitrogen oxide adsorbent due to sulfur poisoning so that the fuel can fully perform even with fuels that contain a large amount of sulfur components. Means for solving the problem

[0012] In order to solve the above-described problem, the basic invention described in claim 1 of the present application is an exhaust gas purification apparatus installed in an exhaust passage of an internal combustion engine or a combustion device, wherein a nitrogen oxide adsorbent is provided in the exhaust passage. The nitrogen oxide adsorbents are manganese (Mn), nickel (Ni), cobalt (Co), vanadium (V), chromium (Cr), iron (Fe), titanium (Ti), scandium (Sc ) And yttrium (Y), at least one element A and a lithium composite oxide represented by the general formula LiAxOy or LiAxP04 having lithium (Li) as constituent elements. For example, it is formed of a lithium composite oxide such as lithium manganate (LiMn 2 O 3), lithium titanate (Li TiO 2), or mangan lithium phosphate (LiMnPO 4).

[0013] Composite oxides of alkali metal lithium (Li) and transition metals such as manganese (Mn) are currently produced in large quantities as positive electrode materials for lithium-ion batteries and are now on the market. It can be obtained easily and inexpensively. As a result, the cost of the apparatus can be reduced, and the inclusion of a transition metal such as manganese (Mn) makes it easier to react with lattice oxygen, so that NO can be rapidly oxidized to NO. Saturated N0x adsorption amount can be increased, and N0x adsorption capacity is improved.

[0014] The invention according to claim 2 is the exhaust gas purifying apparatus according to claim 1, wherein a noble metal is added to the nitrogen oxide adsorbent.

[0015] When the noble metal is added as in the above configuration, the cost of the apparatus is higher than when no noble metal is included, but the entire nitrogen oxide adsorbent is inexpensive and in large quantities distributed in the market. The ability to use battery positive electrode materials prevents N

Ox absorption ability can be improved.

[0016] The invention according to claim 3 is the exhaust gas purifying apparatus according to claim 2, wherein the noble metal is platinum (Pt) and the lithium composite oxide is lithium titanate (Li TiO).

[0017] By using lithium titanate to which platinum is added as a noble metal (Pt—LiTiO) as in the above configuration, SOx resistance is improved, and poisoning of the nitrogen oxide adsorbent is prevented. Life can be extended.

[0018] The invention according to claim 4 is the exhaust gas purifying apparatus according to any one of claims 1 to 3, wherein the nitrogen oxide adsorbent is aluminum oxide (Al 2 O 3) and / or anatase type. It is supported on a carrier made of titanium oxide (TiO 2).

[0019] As described above, when the nitrogen oxide adsorbent is supported on a porous carrier having a large specific surface area, the NOx absorption capacity is further improved. Anatase-type titanium oxide (TiO) is stable at low temperatures and has a large comparative surface area compared to rutile-type titanium oxide that is stable at high temperatures.

[0020] The invention according to claim 5 is the exhaust gas purifying apparatus according to any one of claims 1 to 4, wherein the nitrogen oxide adsorbent is an additive amount as lithium oxide (Li 2 O). Is 10-20% by weight.

[0021] When lithium oxide (LiO) is added at a weight ratio as described above, the Nx absorption capacity is further improved.

[0022] The invention according to claim 6 is the exhaust gas purification device according to any one of claims 1 to 5, wherein the nitrogen oxide adsorbent is fired within a range of 400 ° C to 500 ° C. To do.

[0023] By firing within the temperature range as described above, a large specific surface area can be secured, the amount of saturated NOx adsorbed can be increased, and the NOx absorption capacity can be further improved. Most preferably, firing is performed at approximately 450 ° C.

[0024] The invention according to claim 7 is the exhaust gas purifying device according to any one of claims 2 to 6, wherein the adsorbed substance desorbing means is disposed upstream of the nitrogen oxide adsorbent in the exhaust gas, A combustion device is arranged downstream of the oxide adsorbent exhaust.

[0025] According to the above configuration, nitrogen oxides such as NO and NO are likely to be generated during normal operation of the internal combustion engine, particularly during normal operation under excessive air conditions.

Nitrogen oxides such as O are temporarily adsorbed by the nitrogen oxide adsorbent. Then, when the NOx adsorption amount reaches a predetermined value, the nitrogen oxide desorbing means and the combustion device are operated to perform a regeneration operation. In this regeneration operation, first, nitrogen oxide is desorbed by the adsorbent desorbing means while the nitrogen oxide adsorbing material is heated or reduced. When the noble metal is not included in the nitrogen oxide adsorbent, most of the NOx is desorbed in the form of nitrogen oxides such as NO and N0, and these desorbed NOx is the fuel rich concentration of the downstream combustion device. It is reduced to N in the combustion area, detoxified and discharged.

[0026] Further, in the regeneration operation, the fuel-rich combustion region of the adsorbent detachment means or the combustion device When CO and hydrocarbons are generated in this process, these CO and hydrocarbons are oxidized to CO and HO in the fuel lean combustion zone of the combustor, detoxified and discharged. In addition, since the combustion temperature is low in the fuel lean combustion region of the combustion apparatus, N2 desorbed by the adsorbed material desorbing means will not be oxidized again and will not return to nitrogen oxides.

[0027] In this way, by arranging the combustion device downstream of the nitrogen oxide adsorbent, even with an inexpensive nitrogen oxide adsorbent that does not contain a noble metal, it is the same as when a catalyst containing a noble metal is used. It is economical because nitrogen oxides in the exhaust gas can be made harmless and discharged. In addition, normal operation and regenerative operation can be performed without complicated lean and rich control on the engine side.

[0028] The invention according to claim 8 is the exhaust gas purifying apparatus according to any one of claims 3 to 7, which refers to claim 2 or claim 2, wherein the combustion apparatus is a lean fuel combustion system. It is.

[0029] According to the above configuration, when the nitrogen oxide adsorbent contains a noble metal, most of the substance that desorbs the nitrogen oxide adsorbent is reduced to the N state by the catalytic action of the noble metal. Therefore, the combustion device disposed downstream is a combustion device that performs only lean fuel combustion that renders only CO and hydrocarbons harmless, thereby saving fuel consumption.

[0030] The invention according to claim 9 is the exhaust gas purifying apparatus according to any one of claims 3 to 7, wherein the temperature of the adsorbed substance desorbing means is set to be near or lower than the firing temperature. Yes. For example, if the firing temperature is 450 ° C, control should be done so that it burns near 450 ° C or below.

[0031] As described above, by suppressing the temperature at the time of desorption of nitrogen oxides to near or below the firing temperature, sintering and loss of lithium (Li) are prevented, thereby suppressing performance deterioration. The life of the nitrogen oxide adsorbent can be extended.

[0032] The invention according to claim 10 is the exhaust gas purifying apparatus according to claim 1, wherein a sulfur oxide adsorbing material is arranged upstream of the nitrogen oxide adsorbing material.

[0033] With the above configuration, during normal operation of the internal combustion engine, sulfur oxide in the exhaust gas is adsorbed by the sulfur oxide adsorbent before reaching the nitrogen oxide adsorbent, so that the nitrogen oxide adsorbent Prevent sulfur poisoning from reducing the amount of nitrogen oxide adsorbed by sulfur poisoning You can In addition, durability is improved. In particular, lithium composite oxides composed of transition metal elements other than titanium (Ti) (for example, LiMn O) contain titanium (Ti).

twenty four

Compared with the low sulfur absorption, the sulfur oxide adsorbent can be prevented from being poisoned as described above.

[0034] The invention according to claim 11 is the exhaust gas purifying apparatus according to claim 10, wherein the sulfur oxide adsorbing material includes copper oxide and zirconium oxide.

[0035] According to the above configuration, since the copper oxide and the zirconium oxide have an excellent ability to absorb sulfur oxide (Sx), the amount of sulfur oxide adsorbed can be increased.

[0036] The invention according to claim 12 is the exhaust gas purifying apparatus according to claim 11, wherein the sulfur oxide adsorbent has a metal ratio of copper to zirconium of 1: 1.

[0037] With the above configuration, the amount of sulfur oxide adsorbed can be increased.

[0038] The invention according to claim 13 is the exhaust gas purifying device according to claim 11 or 12, wherein an adsorbent detachment means is disposed upstream of the sulfur oxide adsorbent, and the nitrogen oxide adsorbent A combustion device is disposed downstream of the exhaust.

[0039] Since copper oxide and zirconium oxide can reversibly absorb and desorb sulfur oxides, nitrogen oxide desorbing means is provided upstream of the nitrogen oxide adsorbent, and a combustion device is provided downstream. By switching between normal operation and regenerative operation in the exhaust gas purification device, nitrogen oxide is adsorbed by the nitrogen oxide adsorbent at the time of excessive air combustion in normal operation, and at the same time, sulfur oxide is adsorbed by the sulfur oxide adsorbent. Adsorbed and then desorbs the nitrogen oxides and sulfur oxides adsorbed on each adsorbent during the excessive fuel combustion in the regeneration operation, and the nitrogen oxides are detoxified by the downstream combustion device and discharged. be able to.

[0040] The invention according to claim 14 is an exhaust gas purification device installed in an exhaust passage of an internal combustion engine or a combustion device, wherein nitrogen oxide is temporarily adsorbed in an excess air atmosphere, and the adsorbed nitrogen oxide A nitrogen oxide adsorbent that desorbs a substance in a temperature rising or reducing atmosphere, and an adsorbent desorbing means that is disposed upstream of the nitrogen oxide adsorbing material and makes the inside of the exhaust passage a temperature rising or reducing atmosphere; A combustion device disposed downstream of the nitrogen oxide adsorbent from the exhaust gas, and the nitrogen oxide adsorbent is made of a metal oxide containing no noble metal.

[0041] In the above exhaust gas purification device, when the engine is normally operated, in particular, excessive air Nitrogen oxides such as NO and NO are likely to be generated during normal operation under conditions, but the generated nitrogen oxides such as NO and NO are temporarily adsorbed by the nitrogen oxide adsorbent. Then, when the NOx adsorption amount reaches a predetermined value, the nitrogen oxide desorbing means and the combustion device are operated and the regeneration operation is performed. In this regeneration operation, first, nitrogen oxides are desorbed by the adsorbate desorbing means with the nitrogen oxide adsorbent as a temperature rising or reducing atmosphere. Since the nitrogen oxide adsorbent contains no precious metal, most of the nitrogen oxides are desorbed in the form of nitrogen oxides such as N0 and N0, and the amount desorbed in the N state is small, but nitrogen oxide adsorption is not possible. In the fuel rich combustion region of the combustion system downstream from the material, Nx is reduced to N, detoxified and discharged.

[0042] On the other hand, CO, hydrocarbons, and the like generated in the fuel rich combustion region of the combustion device are oxidized to C0 and discharged in the air excess combustion region of the combustion device. Since the combustion temperature is low in the excessive air combustion region, N produced in the fuel rich combustion region is not oxidized again and does not return to nitrogen oxides.

[0043] In this way, by arranging the combustion device downstream of the nitrogen oxide adsorbent, the inexpensive nitrogen oxide adsorbent that does not contain the noble metal is used in the same manner as when the catalyst containing the noble metal is used. It is economical because nitrogen oxides in exhaust gas can be made harmless and discharged. In addition, normal operation and regenerative operation can be performed without complicated lean and rich control on the engine side.

[0044] The invention according to claim 15 is the exhaust gas purification device according to claim 14, wherein the nitrogen oxide adsorbing material is a transition metal oxide.

[0045] When a transition metal oxide is used as in the above configuration, NO that easily reacts with lattice oxygen can be rapidly oxidized to N0, and the saturation of nitrogen oxide adsorbent N0x Adsorption amount and Nx adsorption amount per unit time can be increased.

[0046] The invention according to claim 16 is the exhaust gas purifying apparatus according to claim 15, wherein the transition metal oxide constituting the nitrogen oxide adsorbent includes manganese oxide and zirconium oxide.

[0047] According to the above configuration, since the manganese oxide has a strong oxidizing ability, the saturated NOx adsorption amount of the nitrogen oxide adsorbent that easily generates NO and the NOx adsorption amount per unit time are increased. That power S.

[0048] The invention according to claim 17 is the exhaust gas purifying apparatus according to claim 16, wherein the compounding ratio of manganese oxide and zirconium oxide in the nitrogen oxide adsorbent is 1: 1 as a metal ratio. .

[0049] According to the above configuration, in the transition metal oxide containing manganese oxide and zirconium oxide, the saturated N0x adsorption amount of the NOx adsorbent can be increased as much as possible.

[0050] The invention according to claim 18 is the exhaust gas purifying apparatus according to claim 16 or 17, wherein the nitrogen oxide adsorbent further contains yttrium oxide.

[0051] When yttrium oxide is added as in the above configuration, it becomes easier to form nitrate, so it becomes possible by reacting with the generated NO and absorbing nitrogen oxide in the form of nitrate,

2

Saturated N0x adsorption amount can be further increased.

[0052] The invention according to claim 19 is the exhaust gas purifying apparatus according to claim 18, wherein the yttrium oxide is from 0.:! To 0.5% by weight of the entire nitrogen oxide adsorbent.

[0053] When yttrium is added within the above range, the increase in the amount of saturated NOx adsorbed is significant.

In particular, it increases most around 0.2% by weight.

[0054] The invention according to claim 20 is the exhaust gas purifying apparatus according to claim 16, wherein the nitrogen oxide adsorbing material further contains aluminum oxide.

[0055] The aluminum oxide as described above is used as a support for manganese oxide and zirconium oxide, but the aluminum oxide is porous and has a high surface area. As a result, the amount of saturated NOx adsorbed and the amount of NOx adsorbed per unit time increase.

[0056] The invention according to claim 21 is the exhaust gas purifying device according to claim 20, wherein the nitrogen oxide adsorbing material is a ratio of manganese oxide and zirconium oxide to 3 to 3 of the entire nitrogen oxide adsorbing material: 10% by weight.

[0057] As described above, when manganese oxide and zirconium oxide are 3 to 10% by weight of the entire nitrogen oxide adsorbent, the saturated NOx adsorption amount and the N0x adsorption amount per unit time are reduced. It increases, especially at around 5%.

[0058] The invention according to claim 22 is the exhaust gas length device according to claim 15, wherein the nitrogen The oxide adsorbent is made of a transition metal oxide containing cobalt oxide and zirconium oxide.

[0059] Cobalt oxide has the same strong oxidizing ability as manganese oxide described in claim 15, and thus, NO is also generated by including cobalt oxide. Easy to increase NOx storage.

[0060] The invention according to claim 23 is the exhaust gas purifying device according to claim 22, wherein the nitrogen oxide adsorbent is comprised of cobalt oxide in an amount of 0.:! To 1 wt% of the entire adsorbent.

[0061] As described above, in the transition metal oxide containing cobalt oxide and zirconium oxide, if the cobalt oxide is contained in the range of 0.:! To 1 wt% of the entire adsorbent, Saturation N0x adsorption amount and Nx adsorption amount per unit time increase, especially at 0.5% by weight.

[0062] The invention according to claim 24 is the exhaust gas purifying apparatus according to any one of claims 14 to 23, wherein a sulfur oxide adsorbing material is disposed upstream of the nitrogen oxide adsorbing material.

[0063] With the above configuration, the sulfur oxide in the exhaust gas is adsorbed by the sulfur oxide adsorbent on the upstream side of the exhaust gas before reaching the nitrogen oxide adsorbent. It is possible to prevent a decrease in NOx adsorption due to sulfur poisoning without being poisoned. It also improves durability.

[0064] The invention according to claim 25 is the exhaust gas purifying apparatus according to claim 24, wherein the sulfur oxide adsorbing material includes copper oxide and zirconium oxide.

[0065] According to the above configuration, copper oxide and zirconium oxide have an excellent ability to absorb sulfur oxide (S0x), and can reversibly absorb and desorb sulfur oxide. By switching between normal operation and regeneration operation in an exhaust gas purification device equipped with a nitrogen oxide desorption means upstream of the oxide adsorbent and a combustion device downstream, during excess air combustion in normal operation At the same time, the nitrogen oxide is adsorbed by the nitrogen oxide adsorbent, and at the same time the sulfur oxide is adsorbed by the sulfur oxide adsorbent. Each sulfur oxide can be desorbed and a small amount of nitrogen oxide can be made harmless by the downstream combustion device and discharged. [0066] The invention according to claim 26 is the exhaust gas purifying apparatus according to claim 24, wherein the metal ratio of the copper and zirconium is 1: 1.

[0067] With the above configuration, the amount of sulfur oxide adsorbed can be increased.

[0068] The invention according to claim 27 is the exhaust gas purification device according to claim 24, wherein the sulfur oxide adsorbing material includes a noble metal and a lithium titanium composite oxide.

[0069] With the above configuration, as in the sulfur oxide adsorbent using the copper oxide and zirconium oxide of claim 12, the sulfur oxide together with the nitrogen oxide is effectively rendered harmless and discharged. That power S. The invention's effect

In summary, according to the present invention, a lithium composite oxide containing lithium (Li) used as a positive electrode material of a lithium ion battery and a transition metal such as manganese (Mn) is used as a nitrogen oxide adsorbent. By using it, it is possible to provide a nitrogen oxide adsorbent that is inexpensive and has a good N0x absorption capacity, and thereby it is possible to provide an exhaust gas purification device that is inexpensive and has a large amount of saturated NOx adsorption. In particular, as the lithium-titanium composite oxide, by using lithium titanate to which platinum is added, or by arranging a sulfur oxide adsorbent on the exhaust upstream side of the nitrogen oxide adsorbent, the nitrogen oxide adsorbent Can also be prevented.

[0071] Further, by providing a low-cost nitrogen oxide adsorbent made of a metal oxide containing no noble metal, particularly a transition metal oxide, the cost of the apparatus can be reduced, while the nitrogen oxide can be easily and It can effectively detoxify and discharge.

Brief Description of Drawings

FIG. 1 is a schematic view of a first embodiment of an exhaust gas purification apparatus to which the present invention is applied.

FIG. 2 is a schematic view of a second embodiment of an exhaust gas purification apparatus to which the present invention is applied.

[Fig. 3] Comparison of saturated NOx adsorption amounts of LiMn O, LiMnPO, and Pt-Li TiO

2 3 4 2 3

The

[Fig. 4] NOx adsorbent made of Pt—Li TiO of the present invention and Pt—Ba 0 type of comparative example

2 3 2 This figure shows the difference in the amount of saturated NOx adsorbed from the formed NOx adsorbent, showing the case where SO X is included in the exhaust gas, the case where SO X is included, and the case where SO X is included.

[Fig.5] When the weight ratio of the Nx adsorbent made of Pt—Li TiO and the carrier is changed It is a figure which shows the change of saturated NOx adsorption amount.

[Figure 6] Additive amount of lithium oxide (Li 2 O) and saturated NOx adsorption amount in NOx adsorbent

2

It is a figure which shows the relationship.

Fig. 7] is a diagram showing the relationship between the firing temperature and the specific surface area when making the ΝΟχ adsorbent.

8] A graph showing the relationship between the temperature of the adsorbent desorbing means and the saturated NOx adsorption amount when the firing temperature of the χχ adsorbent is 450 ° C.

FIG. 9] is a diagram showing the component ratio of a substance that desorbs NOx adsorbent force according to the present invention.

FIG. 10 is a graph showing the amount of saturated Nx adsorbed on NOx adsorbents by various transition metal oxides.

FIG. 11 is a graph showing saturated Nx adsorption amounts at various metal ratios in Nx adsorbents composed of manganese oxide and zirconium oxide.

[Fig.12] Diagram showing the change in the amount of saturated Nx adsorbed with respect to the change in the amount of yttrium oxide added to the Nx adsorbent composed of manganese oxide and zirconium oxide in the structure where yttrium oxide is added. It is.

[Figure 13] NOx adsorbent in which aluminum oxide is added to a 1: 1 metal ratio NOx adsorbent consisting of manganese oxide and zirconium oxide, saturation with respect to changes in the overall proportion of manganese oxide and zirconium oxide It is a figure which shows the change of NOx adsorption amount.

FIG. 14 is a diagram showing a change in saturated NOx adsorption amount with respect to a change in addition amount of conoult in a NOx adsorbent composed of cobalt oxide and zirconium oxide.

FIG. 15 is a diagram showing a component ratio of a desorbed substance of a conventional nitrogen oxide storage catalyst containing a noble metal.

Explanation of symbols

1 Internal combustion engine

2 Exhaust passage

2a, 2b Branch exhaust passage

2c Downstream exhaust passage

3 Adsorbent desorption means

4 NOx adsorbent

5 Combustion device 40 particulate filter

42 S0x adsorbent

XI Fuel rich combustion region

X2 Fuel lean combustion region

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment of the Invention]

FIG. 1 shows an embodiment of an exhaust gas purifying apparatus according to the present invention. An internal combustion engine 1 or an exhaust passage 2 of a combustion device is branched into first and second branched exhaust passages 2a and 2b. A switching valve 20 is provided at the branch portion on the exhaust upstream side, and both branch exhaust passages 2a and 2b merge at the end portion on the exhaust downstream side and are connected to the downstream exhaust passage 2c. By switching the switching valve 20, the exhaust gas from the internal combustion engine 1 is selectively discharged into one of the branch exhaust passages 2a, 2b, and the remaining branch exhaust passage can be regenerated. Examples of the internal combustion engine 1 include a diesel engine, a gas engine, a gasoline engine, or a gas turbine engine, and examples of a combustion device include an industrial boiler, which are mainly operated under an excess air condition.

[0075] In each of the branch exhaust passages 2a and 2b, the adsorbed substance desorbing means 3, the particulate adsorption filter 40, the nitrogen oxide adsorbing material (hereinafter referred to as "NOx adsorbing material") 4 in order from the exhaust upstream side. And the combustion device 5 is arranged at intervals in the exhaust flow direction.

[0076] NOx adsorbent 4 is a transition metal, in particular, manganese (Mn), nickel (Ni), covanoleto (Co), vanadium (V), chromium (Cr), iron (Fe), titanium (Ti), scandium. Of the element group of (Sc) and yttrium (Y), it is formed of a lithium composite oxide represented by the general formula LiAxOy or LiAxPO having at least one element A and lithium (Li) as constituent elements. General

Four

As a specific example conforming to the formula LiAxOy, for example, lithium manganate (LiMn 2 O 3)

2 4 There is lithium tanoate (Li TiO), and as a specific example conforming to the above general formula LiAxPO

2 3 4

Includes lithium manganese phosphate (LiMnPO 4).

Four

[0077] In the present embodiment, a material obtained by further adding a noble metal platinum (Pt) to the lithium composite oxide is used, and in order to maintain high NOx absorption capacity and SOx resistance, the lithium composite oxide is used. Lithium titanate (Li Ti〇) containing titanium (Ti) as a constituent element

2 3 [0078] Further, the nitrogen oxide adsorbent 4 has an addition amount of 10 to 20 times as lithium oxide LiO.

2

The amount is in the range of 400 ° C. to 500 ° C. Preferably approximately 450. Bake with C.

[0079] Further, in this embodiment, aluminum oxide (Al 2 O 3) and / or anatase type oxide

twenty three

The above platinum and lithium titanate (Li TiO) are supported on a carrier made of tantalum (TiO 2).

2 2 3

The

[0080] The adsorbed substance desorbing means 3 arranged on the most upstream side of the exhaust gas is composed of a fuel nozzle 31, an ignition device 32, and an air supply means 33. The fuel nozzle 31 passes through the fuel metering device 10. The fuel supply amount and the supply timing are controlled by an electronic control unit (hereinafter referred to as “ECU”) 12. The air supply means 33 is connected to the air supply source 17 via the air metering device 16, and the air metering device 16 is controlled by the ECU 12 so that the air supply amount and the supply timing are controlled. By controlling the fuel supply amount and supply timing as well as the air supply amount and supply timing as described above, for example, fuel rich combustion is performed, and the temperature in the corresponding branch exhaust passage 2a or 2b is raised and reduced at the same time. It can be.

[0081] The fuel supply amount and the air supply are set such that the combustion temperature of the adsorbent desorption means 3 is close to or below the firing temperature (400 ° C to 500 ° C) of the nitrogen oxide adsorbent 4. The amount is set. For example, if the firing temperature is 450 ° C, it is set to around 450 ° C or lower.

[0082] Combustion device 5 arranged on the most downstream side includes fuel nozzle 6, ignition device 7 and air supply means 15, and in the operating state of combustion device 5, the exhaust upstream side and downstream side of air supply means 15 The fuel rich combustion region XI and the fuel lean combustion region X2 can be formed. The fuel nozzle 6 is connected to a fuel tank 11 via a fuel metering device 10, and the amount and timing of fuel supply are controlled by an electronic control unit 12. The air supply means 15 is connected to an air supply source 17 via an air metering device 16, and the air metering device 16 is controlled by an ECU 12 for the air supply amount and the supply timing.

[0083] When the NOx adsorbent 4 does not contain a noble metal such as platinum, the combustion apparatus 5 has a fuel rich combustion region XI on the exhaust upstream side and downstream side of the air supply means 15 as described above. Burning The fuel supply amount and the air supply amount are controlled so as to form the lean-burning region X2, but if the NOx adsorbent 4 contains a noble metal such as platinum as in this embodiment, the fuel supply amount It is also possible to reduce the fuel consumption and increase the air supply amount so that only the lean fuel combustion region X2 is formed.

[0084] (Effects of Embodiment)

When operating the internal combustion engine 1, the switching valve 20 switches the connection destination of the exhaust passage 2 so that one of the branched exhaust passages 2a and 2b is used as the exhaust gas exhaust passage of the internal combustion engine 1. The other is regenerated as required. The state of FIG. 1 is a state in which the second branch exhaust passage 2b is used as an exhaust gas discharge passage of the internal combustion engine 1 and the first branch exhaust passage 2a is used for regeneration operation.

[0085] During operation of the internal combustion engine 1, the combustion device 5 and the adsorbed substance desorbing means 3 are stopped in the second branch exhaust passage 2b used as the exhaust gas discharge passage in FIG. The internal combustion engine 1 is operated under an excess air condition, and therefore there is a high possibility that the exhaust gas contains a small amount of CO, but contains a lot of NOx. This exhaust gas flows from the exhaust passage 2 into the second branch exhaust passage 2b. First, particulate matter is removed by the particulate filter 40, and NOx is adsorbed by the NOx adsorbent 4, and is made harmless and downstream. It is discharged through the side exhaust passage 2c.

[0086] On the other hand, in the first branch exhaust passage 2a that performs the regeneration operation, the combustion device 5 and the adsorbed substance desorbing means 3 are operated. In the adsorbed substance desorbing means 3, the fuel from the fuel nozzle 31 is discharged. By burning with air from the air supply means 33, high-temperature air is supplied to the NOx adsorbent 4, and NOx is desorbed from the NOx adsorbent 4. That is, the NOx adsorbent 4 is regenerated. In this case, since the combustion temperature of the adsorbent desorption means 3 is near or below the firing temperature of the NOx adsorbent 4, sintering does not occur and lithium (Li) does not disappear.

[0087] When platinum (Pt) is added to the N0x adsorbent 4 as in this embodiment, during the regeneration operation, NOx is reduced to N2 by the catalytic action of platinum and rendered harmless. It is desorbed and discharged.

[0088] When noble metal is not added to the NOx adsorbent 4, the combustion device 5 is used as described above. Forms a fuel rich combustion region XI and a fuel lean combustion region X2, which reduces Nx desorbed from the NOx adsorbent 4 to N in the fuel rich combustion region XI. .

2

[0089] In the lean fuel combustion region X2 of the combustion apparatus 5, CO and hydrocarbons are oxidized and CO and

2 Detoxified by H0 etc. and discharged. In the lean combustion zone X2, the combustion temperature is

2

N2 is not oxidized because it is low. If no precious metal is added to the NOx adsorbent 4, CO and hydrocarbons may be generated in the fuel rich combustion zone XI. Oxidized and detoxified in lean burn zone X2.

[0090] When the N0x adsorption amount of the NOx adsorbent 4 in the second branch exhaust passage 2b reaches a predetermined amount (saturation amount or a prescribed amount less than that) by performing normal operation several times, the switching valve 20 Is switched to the first branch exhaust passage 2a side, the combustion device 5 in the first branch exhaust passage 2a and the adsorbate desorption means 3 are stopped, while the combustion device 5 in the second branch exhaust passage 2b and Activate adsorbent desorption means 3. That is, the normal operation is performed in the first branch exhaust passage 2a, and the regeneration operation is performed in the second branch exhaust passage 2b at the same time.

[0091] (Effects of Embodiment)

(1) As shown in Fig. 1, the exhaust passage 2 of the exhaust gas purification device is split into two branch exhaust passages 2a and 2b. One is used as an exhaust gas exhaust passage during normal operation, and the other is used as the engine exhaust passage. Since it is shut off from the exhaust passage 2 and the nitrogen oxide desorbing means 3 and the combustion device 5 are operated to perform the regeneration operation, it is used for desorbing adsorbed substances and for the combustion device related to the amount of exhaust gas from the internal combustion engine 1. Therefore, it is possible to save the fuel supply amount of the adsorbed substance desorbing means 3 and the fuel supply amount in the combustion device 5. Of course, regenerative operation can be performed without performing complicated lean-rich control on the engine side.

[0092] (2) The particulate filter 40 is disposed upstream of the N0x adsorbent 4, so that the particulate filter 40 is particulate during normal operation (when used as an exhaust gas exhaust passage). The exhaust gas from which the substance has been removed can be allowed to flow into the NOx adsorbent 4, and the NOx adsorption rate can be prevented from decreasing due to the N0x adsorbent 4.

[0093] (3) When noble metal platinum (Pt) is added to the N0x adsorbent 4, the amount of saturated NOx adsorbed can be greatly increased. That is, Fig. 3 shows the addition of precious metal as a lithium composite oxide. Lithium manganate not added (LiMnO) and manganate phosphate not added noble metal

Three

Lithium titanate (Pt—Li T) with the addition of lithium (LiMnPO 4) and the noble metal platinum (Pt)

4 2 i〇) Saturated NOx adsorption amount comparison graph, manganese with no precious metal added

Three

Necessary and sufficient saturation with lithium phosphate (LiMnO) and lithium manganese phosphate (LiMnPO) N

3 4

Power to secure Ox adsorption amount In the case of lithium titanate (Pt—Li Ti〇) with platinum added

2 3 includes lithium manganate (LiMnO) and lithium manganese phosphate (LiMnPO 4).

3 4 Saturated N0x adsorption amount of 2 to 3 times can be secured, and it can be seen that the NOx adsorption performance is excellent.

[0094] (4) When lithium titanate (Li TiO) is used as the N0x adsorbent 4, the S0x resistance is excellent.

twenty three

NOx adsorbent 4 can be provided, which can prevent poisoning of Nx adsorbent 4 and extend its life. Fig. 4 is a graph showing SOx resistance of Nx adsorbent 4, and the two graphs on the left side described as the present invention show NOx adsorption formed from lithium titanate (Pt Li TiO) with platinum added. It is material 4 and the two on the right side described as a comparative example

twenty three

The graph shows NOx adsorbent 4 made of barium oxide with platinum added (Pt-BaO system). Each hatched graph shows the case where the exhaust gas flowing through NOx adsorbent 4 does not contain SOx. The cross-line graph shows the amount of saturated NOx adsorbed when 300 ppm of SOx is contained in the exhaust gas flowing through the NOx adsorbent 4. As can be seen from the graph in Fig. 4, NOx adsorption formed with lithium titanate (Pt—Li TiO) doped with platinum.

twenty three

In material 4, even when SOx is included in the exhaust gas, the same amount of saturated NOx adsorption is secured as when SOx is not included. On the other hand, in the case of barium oxide with platinum added (Pt-BaO series), when the exhaust gas contains SOx, the saturated NOx adsorption amount is greatly reduced.

[0095] (5) Fig. 5 shows a Nx adsorbent formed of platinum titanate lithium titanate (Pt_Li TiO).

twenty three

4 and aluminum oxide (Al 2 O 3) and / or titanium oxide (Ti

twenty three

O) is a graph showing the change in the saturated N0x adsorption amount when the weight ratio is changed,

2

When the weight ratio of the carrier is 0 to 80%, the amount of saturated Nx adsorbed increases in proportion to the increase in the carrier. Therefore, the weight ratio of aluminum oxide (Al 2 O 3) should be 80% or more.

twenty three

It is preferable to set it to about 95%. [0096] (6) FIG. 6 is a graph showing the relationship between the amount of addition as lithium oxide (Li 2 O) and the amount of saturated NOx adsorbed for the Nx adsorbent 4, and as can be understood from this graph, It can be understood that when the addition amount as lithium oxide (LiO) is 10 to 20% by weight, the saturated Nx adsorption amount is maintained at the maximum value. Therefore, by adding lithium oxide (LiO) in an amount of 10 to 20% by weight of the entire nitrogen oxide adsorbent, the amount of saturated N0x adsorbed can be increased and the NOx absorption capacity can be improved.

[0097] (7) FIG. 7 is a graph showing the relationship between the temperature at which the Nx adsorbent 4 is calcined, the specific surface area, and the saturated Nx adsorption amount, when the calcining temperature is 450 ° C. And 600 ° C are compared. As can be seen from Fig. 7, a larger specific surface area and a larger saturated N0x adsorption / absorption amount were obtained when the firing temperature was 450 ° C than when the firing temperature was 600 ° C. You can see that the performance is excellent.

(8) FIG. 8 is a graph showing the relationship between the temperature of the adsorbent desorption means 3 and the saturated NOx adsorption amount when the firing temperature of the N 0x adsorbent 4 is 450 ° C. It can be seen that the highest saturated NOx adsorption amount can be obtained at a calcination temperature of around 450 ° C, and that the saturated NOx adsorption amount rapidly decreases both above and below 450 ° C. However, if the temperature of the adsorbent desorption means 3 is higher than the firing temperature, the possibility of sintering and loss of lithium (Li) increases, so the temperature of the desorption means 3 during the regeneration operation is It can be seen that a temperature around 450 ° C is optimal.

[0099] [Second Embodiment of the Invention]

FIG. 2 shows a second embodiment of the exhaust gas purifying apparatus according to the present invention. Compared with the embodiment of FIG. 1, the sulfur oxide adsorbent ( (Hereinafter referred to as “Sx adsorbent”) 42). The rest of the configuration is the same as in Fig. 1, and the same parts are given the same reference numerals.

[0100] In the present embodiment, SxP and the adhering material 42 are oxides of copper and zirconium, and the metal ratio of copper and zirconium is 1: 1.

[0101] (Operation of the embodiment)

Except for the action of the Sx adsorbent 42, it is basically the same as the embodiment of FIG. 1, and only the action of the Sx adsorbent 42 will be described. [0102] During normal operation of the internal combustion engine 1, the SOx in the exhaust gas is adsorbed by the SOx adsorbent 42. As a result, SOx does not flow into the NOx adsorbent 4 and sulfur poisoning of the NOx adsorbent 4 can be prevented. In particular, when a lithium oxide other than lithium titanate (Pt—Li TiO) to which noble metal is added is used as the NOx adsorbent 4, the SOx resistance is low. By placing the SOx adsorbent 42 on the side, the NOx adsorbent 4 can be prevented from being poisoned.

[0103] During the regeneration operation, high-temperature air is also supplied from the adsorbent desorption means 3 to the S0x adsorbent 42, and S0x adsorbed on the S0x adsorbent 42 is desorbed. That is, the SOx adsorbent 42 is regenerated. The detached SOx is discharged as it is. In the regeneration operation, the above N〇x adsorbent 4 is also desorbing as described above, so that S〇x desorbed from the S〇x adsorbent 42 is re-adsorbed on the NOx adsorbent 4. There is no fear of being done.

[0104] As described above, the sulfur oxide adsorbent 42 contains copper oxide and dinoleum oxide, and when the metal ratio of copper to zirconium is 1: 1, the amount of sulfur oxide adsorbed Can increase the power S.

[0105] Further, since copper oxide and dinoleum oxide can reversibly adsorb and desorb sulfur oxides, a nitrogen oxide desorbing means is provided upstream of the nitrogen oxide adsorbent, and a combustion device is provided downstream. By switching between normal operation and regeneration operation in the exhaust gas purification device provided, nitrogen oxide is adsorbed by the nitrogen oxide adsorbent at the time of excessive air combustion in normal operation, and at the same time, sulfur oxide by the sulfur oxide adsorbent After that, during the excessive combustion of fuel in the regeneration operation, nitrogen oxides and sulfur oxides adsorbed on each adsorbent are separated, and the nitrogen oxides are detoxified by the downstream combustion device and discharged. can do.

[Third Embodiment of the Invention]

The NOx adsorbent 4 in the exhaust purification system shown in Fig. 2 uses a metal oxide that does not contain precious metals, and can efficiently adsorb N0x even in an excess air atmosphere and at a predetermined temperature. It has the property of desorbing the adsorbed NOx when the temperature is raised or in a reducing atmosphere. For example, the NOx adsorbent 4 is composed of a transition metal oxide consisting of manganese oxide and dinoleum oxide, and the compounding ratio of manganese oxide and dinoleum oxide is 1: 1. It has become. [0107] In the present embodiment, the S0x adsorbent 42 is an oxide of copper and zirconium, and the metal ratio of copper and zirconium is 1: 1.

[Operation of Embodiment]

In FIG. 2, when the internal combustion engine 1 is operated, the switching valve 20 switches the connection destination of the exhaust passage 2 so that one of the branch exhaust passages 2a and 2b is connected to the exhaust gas exhaust passage of the internal combustion engine 1. And the other is regenerated as required. The state shown in FIG. 2 is a state in which the second branch exhaust passage 2b is used as an exhaust gas exhaust passage of the internal combustion engine 1 and the first branch exhaust passage 2a is used in a regeneration operation.

[0109] During operation of the internal combustion engine 1, the combustion device 5 and the adsorbed substance desorbing means 3 are stopped in the second branch exhaust passage 2b used as the exhaust gas discharge passage in FIG. The internal combustion engine 1 is operated under excessive air conditions, so there is a high possibility that the exhaust gas contains a small amount of CO, but contains a lot of NOx. This exhaust gas flows into the second branch exhaust passage 2b from the exhaust passage 2, and first, particulate matter is removed by the particulate filter 40, and then S0x force S is adsorbed by the SOx adsorbent 42, and NOx NOx is adsorbed by the adsorbent 4, and is exhausted through the downstream exhaust passage 2c in a detoxified state.

[0110] On the other hand, in the first branch exhaust passage 2a to be regenerated, the combustion device 5 and the adsorbed substance desorbing means 3 are operated. In the adsorbed substance desorbing means 3, the fuel from the fuel nozzle 31 is discharged. By burning with air from the air supply means 33, high-temperature air is supplied to the NOx adsorbent 4, and NOx is desorbed from the NOx adsorbent 4. That is, the NOx adsorbent 4 is regenerated.

[0111] The first branch exhaust passage 2a in the regeneration operation state is in a state in which the exhaust gas from the internal combustion engine 1 is blocked and operates independently from the second branch exhaust passage 2b in the normal operation state. Since the regeneration operation is performed by the fuel supply and air supply of the adsorbed material desorbing means 3 and the combustion supply and air supply of the combustion device 5, the adsorbed material desorption and combustion device relating to the amount of exhaust gas from the internal combustion engine 1 is used. Therefore, the amount of fuel supplied from the adsorbent desorption means 3 and the amount of fuel supplied to the combustion device 5 can be saved. During regeneration operation, the adsorbent desorption means 3 is burned in a fuel-rich state, so that the temperature of the Nx adsorbent 4 can be raised to a reducing atmosphere at the same time, thereby improving desorption performance. This In addition, NOx is not generated by the combustion of the adsorbent desorption means 3.

[0112] Figure 9 shows the proportion of substances that desorb from the NOx adsorbent 4 during the regeneration operation. The amount desorbed in the state of nitrogen (N2) is about 8% of the total. NO, NO And like NO

The amount of desorption in the state of 2 2 nitrogen oxide (N0x) is 90% or more. Thus, most of the NOx is desorbed in the state of power SNOx, but the desorbed NOx is reduced to harmless N in the fuel rich combustion region XI of the combustion device 5 on the downstream side of FIG. On the other hand, fuel rich combustion

2

In region XI, CO or hydrocarbons are generated, but are oxidized to CO in the downstream lean fuel combustion region X2 and emitted. In the lean combustion zone X2, the combustion temperature is

2

Since it is low, N produced in the combustion rich combustion region XI is not oxidized.

2

[0113] Further, high-temperature air is also supplied to the SOx adsorbent 42 from the adsorbent desorption means 3, and S0x adsorbed on the Sox adsorbent 42 is desorbed. That is, the S0x adsorbent 42 is regenerated. The detached S0x is discharged as it is. In the regeneration operation, the NOx adsorbent 4 is also desorbed as described above, so there is no possibility that the SOx force SNOx adsorbent 4 desorbed from the SOx adsorbent 42 is re-adsorbed.

[0114] By performing normal operation several times, when the NOx adsorption amount of the NOx adsorbent 4 in the second branch exhaust passage 2b reaches a predetermined amount (saturation amount or a prescribed amount less than that), the switching valve 20 is turned off. 1 is switched to the branch exhaust passage 2a side, the combustion device 5 and the adsorbate desorption means 3 in the first branch exhaust passage 2a are stopped, while the combustion device 5 and the adsorbent in the second branch exhaust passage 2b are stopped. Release means 3 is activated. That is, the normal operation is performed in the first branch exhaust passage 2a, and the regeneration operation is performed in the second branch exhaust passage 2b at the same time.

[0115] (Effect of the embodiment)

(1) Figure 10 is a graph comparing the amount of saturated NOx adsorbed by typical transition metal oxides (Daraf). Manganese Mn and cobalt Co are among the most saturated NOx adsorbed, Next, iron Fe, copper Cu, nickel Ni, chromium Cr and so on. This is because, among the transition metal oxides, manganese oxide and cobalt oxide have the property of easily generating NOx having the strongest oxidizing ability. The saturated N0x adsorption amount is almost proportional to the NOx adsorption amount per unit time.Therefore, if manganese oxide is used as the NOx adsorbent 4 as in this embodiment, saturated NOx Adsorption amount and unit time The amount of N0x adsorbed can be increased, so that NOx can be effectively adsorbed and the frequency of regeneration operation can be reduced, which is economical.

[0116] (2) Figure 11 shows the case where a transition metal oxide consisting of manganese oxide and zirconium oxide (a precious metal is not included) is used as the NOx adsorbent 4. This figure shows the amount of saturated NOx adsorbed at various metal ratios with various ratios. As can be understood from the graph, when the metal ratio between manganese and zirconium (Mn: Zr) is 1: 1, the saturated N0x adsorption amount is the largest (Q0), then the metal ratio is 1: 5, and the metal ratio is 1: 9. It decreases in order of metal ratio 5: 1 and metal ratio 9: 1. Therefore, as in this embodiment, by setting the metal ratio of mangan to zirconium to 1: 1, it is possible to secure a large amount of saturated Νχχ adsorption amount as ΝΟχΡ and adhering material 4.

[Fourth embodiment of the invention]

As the NOx adsorbent 4 in the exhaust gas purifying device shown in Fig. 2, yttrium Y oxide is added to the transition metal oxide (metal ratio 1: 1) consisting of manganese oxide and dinolenium oxide. The amount of yttrium oxide added is from 0.:! To 0.5% by weight of the entire NOx adsorbent 4, preferably 0.2% by weight.

[0118] As described above, when yttrium oxide is added to the nitrogen oxide adsorbing material 4, it becomes easy to form nitrate, and reacts with the generated NO to absorb nitrogen oxide in the form of nitrate. This makes it possible to further increase the amount of saturated NOx adsorption.

[0119] Fig. 12 shows the saturation N of NOx adsorbent 4 with respect to changes in the amount of yttrium oxide (YO) added.

The change in Ox adsorption amount shows the saturated NOx adsorption amount Q0 when the yttrium oxide addition amount is 0 wt%, which corresponds to the saturated NOx adsorption amount Q0 when the metal ratio is 1: 1 in Fig. 4. ing. When the amount of yttrium oxide added increases from 0 wt% to approximately 0.2 wt%, the saturated N0x adsorption amount rapidly increases to the maximum value Q3 via the value Q2 at 0.1 wt%, followed by When the amount of yttrium oxide added increases from approximately 0.2 wt% to approximately 0.5 wt%, the saturated N Ox adsorption amount increases from the maximum value Q3 to the 0.1 wt% value Q2. When it gradually decreases to Q4 (<Q2) and the amount of yttrium oxide added exceeds 0.5% by weight, the saturated N0x adsorption amount is maintained at the above value Q4 and should not increase or decrease. I understand. Therefore, the amount of added yttrium oxide is economical to increase the amount of saturated N0x adsorption. As in the present embodiment, the range of 0.:! To 0.5% by weight is preferable, and the vicinity of 0.2% by weight is most preferable.

[Fifth embodiment of the invention]

Addition of aluminum A1 oxide to transition metal oxide (metal ratio 1: 1) consisting of manganese oxide and zirconium oxide as Nx adsorbent 4 placed in the exhaust gas purification system shown in Fig. 2 To do. Aluminum oxide Al O is porous and has a high specific surface area. Utilizing this aluminum oxide as a support, supporting manganese oxide and dinoleum oxide improves the utilization of active sites. However, the amount of saturated ΝΟχ adsorption and N0x adsorption per unit time increase.

[0121] The ratio of manganese and zirconium oxide to the entire NOx adsorbent 4 is in the range of 3 wt% to 10 wt%, and preferably approximately 5 wt%. In other words, the ratio of aluminum oxide is 97 to 90% of the entire NOx adsorbent 4, and preferably about 95%.

[0122] Fig. 13 shows the relationship between the change in the ratio of manganese oxide and dinoleconium oxide to the entire NOx adsorbent 4 and the amount of saturated NOx adsorbed. When the weight% is 0, as shown at the left end of the graph, the aluminum oxide is 100%, and the saturated NOx adsorption amount is almost zero. When the proportion of manganese oxide and zirconium oxide increases from 0% to about 5% by weight, it suddenly increases from the value Q5 at 3% by weight to the maximum value Q6, and further from about 5% to about 30%. When increased to wt%, the NOx adsorption amount decreases from the maximum value Q6 to the value Q7 through the value Q5 at the time of 3 wt%, and when it exceeds 30 wt%, the saturated NOx adsorption amount almost reaches the value Q7. It is a force that is maintained. Therefore, the ratio of manganese oxide and zirconium oxide to NOx adsorbent 4 as a whole is preferably in the range of 3% to 10% by weight in order to effectively increase the amount of NOx adsorbed. Of these, the vicinity of 5% by weight is most preferable.

[Sixth Embodiment of the Invention]

As the Nx adsorbent 4 placed in the exhaust gas purification device shown in Fig. 2, a transition metal oxide made of cobalt Co oxide and zirconium Zr oxide is used. The ratio of cobalt oxide to the total N0x adsorbent 4 should be in the range of 0.1% to 1% by weight, preferably about N 0.5% by weight. Cobalt oxide has almost the same oxidizing power as manganese oxide as described above. As shown in Fig. 10, it can obtain the same amount of saturated NOx adsorption as manganese oxide.

[0124] Figure 14 shows the change in the amount of saturated Nx adsorption with respect to the amount of cobalt oxide added. When the amount of cobalt oxide added increases from 0.1 wt% to approximately 0.5 wt%, The amount of NOx adsorbed increases rapidly from the value Q10 to the maximum value Q11.Subsequently, when the amount of cobalt oxide added increases from approximately 0.5% by weight to approximately 1% by weight, the value increases from the maximum value Q11. It can be seen that when it decreases to <312 (> value (3 10) and further exceeds approximately 1% by weight, it is maintained at the value Q12. Therefore, the amount of cobalt oxide added is economically saturated. In order to increase the amount of N0x adsorbed, the range of 0.:! To 1% by weight is preferred as in the present embodiment, and the range of about 0.5% by weight is most preferable. .

[Seventh embodiment of the invention]

As the SOx adsorbent 42 to be arranged in the exhaust gas purification apparatus shown in Fig. 2, a sulfur oxide adsorbent 42 made of noble metal and lithium titanium composite oxide (Li / TiO) is arranged. Precious metals include platinum Pt and rhodium Rh.

[0126] The sulfur oxide adsorbent 42 composed of a noble metal and a lithium titanium composite oxide has an excellent SOx absorption capacity, similar to the sulfur oxide adsorbent composed of the manganese oxide and zirconium oxide of the first embodiment. In addition, as shown in Fig. 2, the exhaust gas purification device equipped with the adsorbate detachment means 3 and the combustion device 5 can be used as a lean-rich engine on the engine side. Industrial applicability that allows adsorption and desorption without control

[0127] The present invention is used as an exhaust gas purification device for various machines that exhaust exhaust gas, such as internal combustion engines such as diesel engines, gas engines, gasoline engines, and gas turbine engines, or combustion equipment such as incinerators and boilers. Is possible.

Claims

The scope of the claims

[I] An exhaust gas purifying device installed in an exhaust passage of an internal combustion engine or combustion equipment, and a nitrogen oxide adsorbent disposed in the exhaust passage, the nitrogen oxide adsorbent being manganese (Mn) , Nickel (Ni), covanoleto (Co), vanadium (V), chromium (Cr), iron (Fe), titanium (Ti), scandium (Sc) and yttrium (Y), at least one kind An exhaust gas purification device formed of a lithium composite oxide represented by the general formula LiAxOy or LiAxPO, which comprises the elements A and lithium (Li) as constituent elements.

2. The exhaust gas purification device according to claim 1, wherein a noble metal is added to the nitrogen oxide adsorbent.

3. The exhaust gas purifying apparatus according to claim 2, wherein the noble metal is platinum (Pt) and the lithium composite oxide is lithium titanate (Li TiO 3).

[4] The nitrogen oxide adsorbing material according to any one of claims 1 to 3, wherein the nitrogen oxide adsorbing material is supported on a carrier made of aluminum oxide (Al 2 O 3) and / or anatase-type titanium oxide (TiO 2). Exhaust gas purification device.

[5] The exhaust gas according to any one of [1] to [4] above, wherein the nitrogen oxide adsorbent has an additive amount of 10 to 20% by weight as lithium oxide (LiO). Purification equipment.

6. The exhaust gas purifying apparatus according to any one of claims 1 to 5, wherein the nitrogen oxide adsorbent is fired within a range of 400 ° C to 500 ° C.

7. The adsorbent detachment means is disposed upstream of the nitrogen oxide adsorbent on the exhaust side, and a combustion device is disposed on the exhaust downstream side of the nitrogen oxide adsorbent. An exhaust gas purification device according to claim 1.

8. The exhaust gas purification device according to any one of claims 3 to 7, wherein the combustion device is a lean fuel combustion system.

[9] The exhaust gas purification device according to claim 7, wherein the temperature of the adsorbent desorption means is set to be near or lower than the firing temperature.

10. The exhaust gas purifying apparatus according to claim 1, wherein a sulfur oxide adsorbing material is disposed upstream of the nitrogen oxide adsorbing material.

[II] The sulfur oxide adsorbent contains copper oxide and dinoleconium oxide. The exhaust gas purification device according to claim 10.

12. The exhaust gas purifying apparatus according to claim 11, wherein the sulfur oxide adsorbing material has a metal specific power of copper and dinoleconium: 1.

[13] The method according to any one of claims 10 to 12, wherein an adsorbent removing means is disposed upstream of the sulfur oxide adsorbent, and a combustion device is disposed downstream of the nitrogen oxide adsorbent. The exhaust gas purifier according to any one of the above.

[14] In an exhaust gas purification device installed in an exhaust passage of an internal combustion engine or combustion equipment, nitrogen oxides are temporarily adsorbed even in an excess air atmosphere, and the adsorbed nitrogen oxides are desorbed in a heated or reducing atmosphere. A nitrogen oxide adsorbing material,

An adsorbent detachment means that is disposed upstream of the nitrogen oxide adsorbent and makes the inside of the exhaust passage a temperature rising or reducing atmosphere;

An exhaust gas purification device comprising: a combustion device disposed downstream of the nitrogen oxide adsorbent from the exhaust gas, wherein the nitrogen oxide adsorbent is made of a metal oxide containing no precious metal. .

15. The exhaust gas purifying device according to claim 14, wherein the nitrogen oxide adsorbent is made of a transition metal oxide.

16. The exhaust gas purifying device according to claim 15, wherein the nitrogen oxide adsorbing material is made of a transition metal oxide containing manganese oxide and dinoleconium oxide.

17. The exhaust gas purifying apparatus according to claim 16, wherein the compounding ratio of manganese oxide and zirconium oxide in the nitrogen oxide adsorbent is a metal ratio of 1: 1.

[18] The nitrogen oxide adsorbent further includes yttrium oxide.

The exhaust gas purifying device according to 16 or 17.

[19] The exhaust gas purification device according to [18], wherein the yttrium oxide is in an amount of 0.:! To 0.5% by weight of the entire nitrogen oxide adsorbent.

20. The exhaust gas purifying apparatus according to claim 16, wherein the nitrogen oxide adsorbing material further contains aluminum oxide.

21. The exhaust according to claim 20, wherein the nitrogen oxide adsorbent has a ratio of manganese oxide and zirconium oxide of 3 to 10% by weight of the entire nitrogen oxide adsorbent. Gas purification device.

22. The exhaust gas purifying apparatus according to claim 15, wherein the nitrogen oxide adsorbing material comprises a transition metal oxide containing cobalt oxide and zirconium oxide.

23. The exhaust gas purifying apparatus according to claim 22, wherein the nitrogen oxide adsorbent is cobalt oxide in an amount of 0.:! To 1 wt% of the entire adsorbent.

24. The exhaust gas purifying device according to any one of claims 14 to 23, wherein a sulfur oxide adsorbent is disposed upstream of the nitrogen oxide adsorbent.

25. The exhaust gas purifying apparatus according to claim 24, wherein the sulfur oxide adsorbing material contains copper oxide and dinolenium oxide.

26. The exhaust gas purifying device according to claim 25, wherein the sulfur oxide adsorbing material is a metal specific force S1: 1 of copper and dinoleconium.

27. The exhaust gas purifying device according to claim 24, wherein the sulfur oxide adsorbing material contains a noble metal and a lithium titanium composite oxide.